I. Field of the Invention
The present invention relates generally to water filtering and circulating systems for aquariums and, more particularly, to such a system in which the waste material is trapped between the gravel and the bottom of the aquarium where it can be eliminated by decay or backwashing.
II. Description of the Prior Art
Many aquarium systems in present use employ gravel at the bottom of the tank which acts as a filter for the water circulation system. Conventionally, a suction pump draws the water from a chamber formed beneath the gravel so that the water continually flows downwardly onto the gravel in the tank. In this process, waste material and other debris is removed from the water by the gravel which, after a period of time requires washing of the gravel in order to prevent contamination of the tank. The gravel can be effectively washed only by the difficult and time consuming process of removing the gravel from the tank.
Because the previously known aquarium circulating systems produce water flow down onto the top of the gravel, the septic line produced by the decaying impurities and sediment remain near the top surface of the gravel. Consequently, upon the accumulation of too great of an amount of decay upon the gravel, the decay caused by the septic line disadvantageously contaminates the entire aquarium tank.
In my prior U.S. Patent, U.S. Pat. No. 3,738,491, which issued on June 12, 1973, I described an aquarium circulating system which overcame the disadvantages of the aforementioned aquarium systems. In brief, in my prior system the direction of water flow through the gravel is reversed so that the water flows upwardly, instead of downwardly through the gravel. In this fashion, the septic line formed by the decay of waste products and other debris removed from aquarium water remains at or near the bottom of the gravel so that the waste materials decay with less toxic effects on the aquarium and where the septic line is less apt to be accidently disturbed or uncovered. Moreover, the gravel can be effectively cleaned by backflushing so that the removal of the gravel from the tank to clean it is not required.
My prior under gravel aquarium filter, however, suffered several disadvantages in operation. One such disadvantage is that during the operation of my prior device a water and air spray is continuously emitted through vent openings in the upper portion of the device. This water spray is not only distracting when viewing the aquarium but also impinges upon aquarium components such as the aquarium light and the like. This water spray often-times undesirably causes rust and corrosion of these components. Moreover, this water spray also resulted in excessive and rapid water evaporation from the aquarium tank.
A still further disadvantage of my prior device is that the device itself is quite bulky in construction and thus occupies an appreciable volume of the overall aquarium. The bulky construction thus unnecessarily detracts from the overall beauty of the aquarium.